Experimental investigation on hysteretic behavior of circular hollow steel tubular columns after lateral impacts

Abstract The circular hollow steel tubular (CHST) columns have been extensively utilized as the load-carrying members in construction engineering owing to their superior mechanical behaviors. In practical engineering, the CHST columns are likely to be subjected to the combined actions of both the earthquake and impact loads. However, there is a dearth of experimental studies and theoretical analysis on this type of column subjected to the combined actions. This paper performed the quasi-static tests on 27 specimens after lateral impacts and 9 ones without lateral impacts for the comparison. The main variables discussed herein included the wall thickness of steel tubes, impact heights, and axial load levels. The failure modes, hysteretic performance, ultimate capacity, ductility, stiffness degradation, and energy dissipation of specimens were compared and analyzed. Experimental results demonstrate that the impact height exerts a negative effect on the ultimate capacity and deformability of the CHST columns. The overall displacement ductility and total accumulated energy dissipation capacity of the specimens are reduced evidently with the increase of the impact height. Based on the experimental research, a simplified hysteretic model that considers the combined effects of both impact heights and axial load levels were established for the CHST columns by using the regression analysis. The proposed hysteretic model is verified to accurately predict the non-linear cyclic response of CHST columns after lateral impacts during the entire loading process.